Fuel injection valves which operate electromagnetically are well known. With the aid of a magnetic coil which is chargeable by electricity to generate a magnetic flux, a magnetisable armature which may be combined with a valve needle, will be stimulated for movement. Normally, the movement is an axial movement along a valve needle axis of the valve needle.
When the valve needle and the armature are coupled, the valve needle starts moving due to the movement of the armature. Depending on the direction of the movement, a nozzle orifice may be opened with the aid of the valve needle. In order to seal the nozzle orifice when the magnetic coil is not energized, a valve spring is positioned in the fuel injection valve, which urges the valve needle against the nozzle orifice. This means, that the valve needle has to be moved by the aid of the armature against the spring force of the valve spring, when the nozzle orifice is to be opened. When the nozzle orifice is open, a fuel quantity, positioned in the fuel injection valve, may flow through the nozzle orifice into a combustion chamber, normally a combustion chamber of an internal combustion engine.
A combustion process of the internal combustion engine depends among several other criteria, e.g. fuel quantity or fuel temperature or fuel pressure—on the opening and closing of the nozzle orifice. Therefore, an exactly defined opening and closing of the nozzle orifice are very important for reaching an advantageous power rate, fuel consumption and/or emissions of the internal combustion engine.
The magnetic coil may be arranged in a u-shaped coil casing, while the open end of the coil casing may be positioned vis-a-vis of the armature. To achieve a separation of the magnetic coil from the fluid path, a separation disc or separation ring which separates the actuator from the fuel path may be arranged between the armature and the coil casing.
US 2003/0178509 A1 teaches a fuel injection valve comprising a flux washer between the coil casing an the armature. The separation ring provides a magnetic path between an outer casing of the fuel injection valve and an inlet tube. It is made out of a ferritic material.